For NTFS? Significant, it could become slower in several times, you may also start to see these errors:
So, regular defragmentation for NTFS is highly recommended. It’s also enabled by default, unless you disable it.
However, if you see a high defragmentation, it’s advisable to run it manually.
Maybe with a new hashstore backend it may become a not required, see hashstore
Please be aware, this an experimental feature, so it’s not recommended to run on a production node, unless you are ready that it may be lost or disqualified and agreed with that.